utils+helper: Fix to compile against the latest version of ndn-cxx

Change-Id: If922b1c95beea08e5921af5223af042cb173f434
diff --git a/helper/ndn-stack-helper.cpp b/helper/ndn-stack-helper.cpp
index 6e45281..fd319a6 100644
--- a/helper/ndn-stack-helper.cpp
+++ b/helper/ndn-stack-helper.cpp
@@ -61,7 +61,7 @@
 KeyChain&
 StackHelper::getKeyChain()
 {
-  static ::ndn::DummyKeyChain keyChain;
+  static ::ndn::KeyChain keyChain("pib-dummy", "tpm-dummy");
   return keyChain;
 }